The marking of various labels and the like is well known, and especially the marking of shrink tubing to be applied to electrical wiring whereby identification can be made in the form of characters imprinted thereon. However, the prior art application is limited to the installation of prepared tubing with the imprinting done upon typewriters and/or special imprinting devices which are not portable, and which require the logistics of requisition, production and delivery rather than in-the-field or on-the-job preparation and application of said identification tubing. Therefore, it is a general object of this invention to provide a portable marker for the application of indicia upon shrink tubing, to be used by in-the-field or on-the-job technicians.
This invention is concerned with the application of printed shrink tubing onto the end portions of wiring that requires identification. The number of characters needed for identification varies greatly and consequently the length of the tubing changes accordingly. It is thin-walled cross linked polymer tubing or the like, with which this invention is concerned, and which is available in soft initially cured roll form of large cross sectional diameter, and which is to be subjected to heat curing that reduces its diameter for constriction onto the wires to be identified, as circumstances require. The opacity and/or color of the tubing can vary, a white opaque tubing being widely employed. A problem arises in the imprinting of indicia onto such tubing, the roundness or cylindrical convexity making it difficult to imprint complete legible characters thereon. Heretofore, flattened cores or fillers have been inserted into the tubing to substantially occupy the interior thereof and thereby flatten the same preparatory to imprinting; but this process has its limitations to short lengths of tubing and precludes continuous lengths in the supply thereof. I have discovered that a partial shrink of the tubing while held flattened and through the application of controlled heat will harden the tubing sufficiently so that it will remain flat and pliable and supple for establishing a continuous roll supply thereof and for subsequent manipulation onto a wire end where heat is applied for final curing and shrinking thereof. Accordingly, it is an object of this invention to provide a continuous roll supply of flattened partially cured heat shrink tubing.
The imprinting of indicia onto plastic material is widely employed, and for example typewriters have been used to imprint any desired character upon such tubing, utilizing ribbon or tape with pressure transferable material thereon which is applied by pressure onto said tubing surface. It is an object therefore, to utilize such ribbon or tape in a roll supply thereof, as it is supplied for typewriters heretofore employed to mark such tubing. However, with the present invention the ribbon or tape is transported over a continuous length of tubing, as distinguished from being associated with a multiplicity of short lengths of tubing and each of which must be separately aligned and individually handled.
Printing wheels having embossed characters thereon are of course old in the art, and it is a simple matter to index such a wheel into imprinting position relative to a platen or the like. However, such wheels have not been associated with printing of indicia onto shrink tubing of pre-flattened configuration, nor has such a wheel been used to cut a continuous supply supply of shrink tubing to length. With the present invention, the shrink tubing is disposed between a selected embossed character on the wheel and a platen moveable to pinch the tubing against an intervening tape carrying impressible marking material referred to generally as carbon, ink and/or printing material. This combination advantageously utilizes the collapsed and/or flattened condition of the tubing.
An object of this invention is to provide a continuous supply of shrink tubing in cartridge form to be applied to a portable gun-like mechanism that incrementally advances the same for separate and sequential character impressions. It is another object of this invention to provide a complementary and continuous supply of printing tape in cartridge form to be applied to said portable gun-like mechanism that incrementally advances the same for said separate and sequential character impressions. It is also an object of this invention to associate the aforesaid tubing and tape cartridges into a combined unit for simultaneous installation and/or removal from the operational grip mechanism. With the present invention, the grip mechanism includes all of the mechanical features necessary for selectively imprinting the tubing with material from the tape, and to incrementally advance both the tubing and tape after each imprint; also to cut-off the tubing into length as may be desired. It is to be understood however, that either of the said cartridges can be permanently associated with the grip mechanism and individually loaded with tubing and tape of the color and character required respectively.
It is still another object of this invention to provide a manually operable gun-grip mechanism that sequentially imprints (or cuts) and then advances both the tubing and the tape each time it is operated. A feature is the right angular feed relationship of the tubing and tape, and of the gear driven irreversible ratchet drive that simultaneously advances the tubing and tape subsequent to each character impression or cut-off, also the substantially direct lever action of the platen that imprints the selected wheel characters upon the tubing.